Apparatus for producing low temperatures, the liquefaction of gases, and the separation of the constituents of gaseous mixtures.



. No. 728,173. .A 'PATBNTE'D'MAY 12, 1903.

o. LINDE. APPARATUS PoR BRODUGING Low TBMPBRATURBS, THB LIQUB-FAGTIONo11 GASES, AND 'THE SEPARATION. 01* THB GONSTITUBNTS l or GAsEoUsMIXTURES.

APPLIoArIoB FILED :mn 14 1900.l N0 MODEL.

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NiTE STATES PATENT OFFICE.

Patented May 12, 1903.

CARL LINDE, OF MUNICH, GERMANY, ASSIGNOR OF ONE-THIRDlTO CHARLES F.BRUSH, OF CLEVELAND, OHIO.

APPARATUS FOR PRODUCING LOW TEMPERATURES, THE LIQUEFACTION 0F GASES, ANDTHE SEPARATION 0F THE CONSTITUENTS 0F GASEOUS MIXTURES.

SPECIFICATION forming part of Letters Patent No. 728,173, dated May 12,1903 Original application filed July 9, 1895, Serial No. 555,371.Divided and this application filed Tune 14.1900. Serial To al whom itmay concern.-

Be it known that I, CARL LINDE, of Munich, Kingdom of Bavaria,Germany,have in- Vented certain new and useful Improvements in Apparatus forProducing Low Temperatures, the Liquefaction of Gases, and theSeparation of the Constituents of Gaseous Mixtures; and I do herebydeclare the following to be a full, clear, and exact description of theinvention, such aswill enable others skilled in the art to which itappertains to make and use the same.

My invention relates to an improvement in apparatus for producing 10Wtemperatures, the liquefaction of gases, and the separation of theconstituents of gaseous mixtures, and is a division of application No.555,371, filed July 9, 1895.

My invention is designed especially for the purpose of liquefying gasesor mixtures of the same, such as atmospheric air, and also forseparatingr the constituents of gaseous mixtures. The method ofseparating the components of atmospheric air is based upon a fact Wellknown to physicists, that oxygen, although having a boiling-point higherthan nitrogen,can only be'liquetied simultaneously with the nitrogen orpart of it, but that the nitrogen is iirst evaporated on volatilizingthe liquefied mixture, so that the mixture will,

become richer in oxygen the longer the volatilization is continued.

The liquefaction of gases, such as atmospheric air, has hitherto beencarried out by producing successive liquefaction and volatilization ofliquids of gradually-increasing volatility, such as carbonio acid,nitrous oxid, ethelene, and the like. This method, however, has notproved capable of practical application for the purpose of attainingsuch low temperatures as that required for liquefying atmospheric air.My process for reaching such low temperatures is based upon thediscovery made by Joule and Thomson more than forty years ago thatatmospheric air when discharged through a valve from a space underhighpressure into a space maintained at a lower pressure by causing the gasto pass (No model.)

ott' will have a lower temperature, the decrease (T--T) of thetemperature in degrees centigrade being'expressed by the formula T rr'P2 '-.P' (lf 4 T where p2 isgthe higher pressure, p' the lower pressurein atmospheres, T the initial absolute temperature at higher pressurep2, and T' the absolute Ytemperature at lower pressure p. For thedifference (p2-10') of pressure of fifty atmospheres the difference oftemperature is about 13 centigrade for T 283, 14 for T 273, 16.7 forT250, 26.1 for T.200, and L10. 70 for T 160. I make use of this decreasein temperature for gradually reducing thetemperature to 'the desireddegree by establishing a constant forced circulation of the air betweenthe high-pressure space and the low-pressure space, causing the incomingair at high pressure to be cooled by giving up its heat to the outgoingair at low pressure on its way to the compressor, and supplyingadditional air as Vrequired to keep up the pressure I am enabled toliquefy atmospheric air and to practically'separate the oxygen from thenitrogen.

My invention will best be understood when of suitable construction bywhich the air is v received through the T a and valve a at a pressure pand compressed to a pressure p2, the temperature being raised from t tot2, which temperatures,however, may Vary Within certain limits.

K is the refrigerator, into which compressed air of the temperature t2passes from the compressor through the valved pipe band has itstemperature reduced to t3, said refrigerator consisting of a coil cooledby suitable means,

such as cold brine or liquid ammonia.

G is a counter-current apparatus consisting, as shown in the drawing, ofa coiled pipe within a larger coiled pipe creasing, so as to leave anouter annular channel between the pipes and a central channel. Thesepipes should be of great length-say one hundred meters-and should besurrounded by nonconducting material, such as sheeps wool, so as toprevent transfer of heat to the outside and between the windings. Thedrawing showsa casing H for holding the non-conducting material.

The upper end of the inner coiled tube of the counter-current apparatusG is connected to the lower end of the coil of cooler K by a pipe c c',while the discharge-pipe b of the compressor C is connected to the upperend of the cooling-coil, by which means communication is establishedfrom the dischargeopening of the compressor C through the cooler K tothe top of the inner channel of the counter-current apparatus G. The topof the channel formed between the inner and outer coiled pipe of theapparatus G' is connected to the suction end of the compressor C bymeans of the pipe a, T et', and valve z.

P is a primary compressor drawing air from the outside through a pipe dand valve a: and delivering it to the suction of the compressor Cthrough the T a and valve y and s, its object being to supply air at theinitial high pressure 1J'.

V is a closed vessel beneath the countercurrent apparatus, into whichvessel projects a nozzle or expander N, attached to the lower end of theinner coiled pipe of the apparatus G, said nozzle being provided with aregulating-valve R'.

As shown in the drawing, the vessel V at or near its topcommunicates-with the lower part of the space between the inner andouter coiled tubes of the counter-current apparatus G' by a pipe 7o.

The apparatus as so far described has a lowpressure channel extendingfrom the vessel V through the space between the pipes of the apparatus Gto the suction ofthe compressor C and a high-pressure channel extendingfrom the dischargevalve of the compressor C through the cooler K andthrough the inner channel of the counter-current apparatus G' to theregulating-valve R.

The operation of the apparatus so far described is as follows: By theaction ofthe aircompressors the proper pressures are established withinthe apparatus, the difference of pressure between the high and lowpressure spaces being regulated by the valve R. For liquefyingatmospheric air I have found a pressure of twenty-tive atmospheres inthe low-pressure space and seventy-five in the high-pressure space veryeffective. l have also found that cooling the air which leaves thecompressor to a temperature t3 ot' about 10o centigrade, or less, to besufficient. The compressed air at the higher pressure of seventy-fiveatmospheres discharged into the vessel Vl against the initial pressureof twenty-five atmospheres maintained therein has its temperaturelowered to t* and passing at the reduced pressure of twenty-tiveatother.

mospheres through the counter-current apparatus G' it absorbs heat fromthe incoming air at seventy-five atmospheres, so that if the apparatuswere working to perfection the air passing to the counter-currentapparatus at a temperature t3 will have its temperature reduced to t4.The air from the bottom of the counter-current apparatus G now reducedto t4 being discharged against the lower pressure in the vessel V hasits temperature still further reduced to 253, the values of t4 and t3gradually decreasing until a temperature below the critical point isreached. In the counter-current apparatus G the gas reduced to the lowerpressure p' and the gas at the higher pressure p2 and temperature i3travel in opposite directions and on opposite sides along the innercoiled pipe, which is formed of conducting material, so as to effect anexchange of temperatures, whereby the temperature in the vessel V' isfinally lowered to or below the critical point, whereupon air isliquefied and collects at the bottom of the vessel V. critical point isreached, a condition of permanency is established, and while a certainportion of the circulatingairis condensed in the vessel V acorresponding volume of fresh air is supplied by the compressor P, so asto maintain pressures. While in starting the temperature of' the air inthe apparatus is gradually lowered, fresh air must also be supplied tokeep up pressures. For further separating the nitrogen from the oxygenand for producing the latter also in the gaseous state when desired luse an evaporating vessel V2 with an internal coil S and twocounter-current apparatus G2 and G3, constructed similarly to G of twocoiled pipes, one within the A pipe h, with a regulating-valve R2,connects the lower parts ofthe vessels V and V2. The upper end of thevessel V2 is connected to the lower end of the outer tube of thecounter-current apparatus G2, at the upper end of which an outlet forgaseous nitrogenis provided. From near the top of the vessel V2 a pipet' leads to the lower end of the outer pipe of the counter-currentapparatus G3 in such a manner that the overflow from the vessel V2 istrapped on its way to the apparatus G3. Air at the pressure p2 andtemperature i3 is led by the valved pipe e, connected to cross d, to theupper end of the inner pipe of the counter-current apparatus G2 andthence to coil S and also to the inner pipe of apparatus G3, throughpipe f and valve m,and is carried off from the lower ends of apparatusG3 and of coil S by the pipe g to the lower end of the inner pipe of theapparatus g above the regulating-valve R'. Within the vessel V2 nitrogenis evaporated by heat abstracted from theair in coil S and is dischargedthrough the upper end of the outer pipe of the apparatus G2. The liquidoxygen flows from near the top oi".l vessel V2 to the counter-currentapparatus G3, where it is evaporated and discharged in gaseous When the'IIO ' losses.

form from top of the outer pipe. When oxygen is wanted in liquid form,the apparatus G3 is dispensed with and the liquid drawn from the lowerpart of the vessel V2 through valve n. By the arrangement of thecounter-current apparatus G2 and G3 and by car- -rying the cooledair-.back above the valve R the heat required for evaporating nitrogenand oxygen is abstracted from the incoming air, so as to practicallyreduce the work to be done by the machine to what is due to the The lowtemperatures obtained in the counter-current apparatus G2 and G3 may,however, be employed for other purposes.

Of course the apparatus shown and describedmay be greatly varied ormodified, my invention not being restricted to any details ofconstruction. Thus, for instance, the fractional distillation of theliquid may be effected directly within the vessel V instead of V2' byplacing the coil S into Vand then allowing the more volatile gases toescape through the space between the outer and inner tubes of theapparatus G. The remaining countercurrent apparatus G and G3 may be socombined that the transfer of heat from the compressed air is effectedthrough a single supply-pipe, either by arranging three concentric tubesor by having two smaller tubes within a larger one. Thegases leaving theapparatus may be repeatedly subjected tothe process described to insuremore perfect separation and purity. The compressors may be j acketed andcooled by water or cold brine, so that for `small diameters and longstrokes the air may be more or less cooled during compression. kThemodifications are readily understood Without illustrations.

The word condensation as used in'some of the claims means andcomprehends the reduction of the volume of the gas to any desireddegree.

Having fully described my invention, what I claim as new, and desire tosecure by Letters Patent, is

l. A counter-current and gas-liquefying apparatus consisting of ahigh-pressure conduit a gas compressor and cooler for maintaining acirculation of cooled ccmpressed gas through the high-pressure conduit,an expansion-chamber, and a throttle or pressure-reducing valve, throughwhich the compressed gas expands directly into said expansion chamber,in combination with a lowpressure conduit connectedy at one end withsaid expansion-chamber, andadapted to conduct the expanded gasbackwardly over and in direct contact with the high-pressure conduit andcause it to absorb heat to its fullest capacity from the compressed gasabout to be expanded, substantially as set forth.

2. A liqueiier for atmospheric air, consist-v ing of a casing, a pipe insaid casing, means for supplying compressed air to one end of said pipe,and an expander at the other end, the parts being so arranged that theairas it leaves the expander passes back over the pipe whereby upo'iicontinuous operation the air is liquefied, substantially as described.

3. A liquefler for atmospheric air provided; with a pipe to which airunder pressure is sup-4 plied combined'with an expansion valve or nozzlevand-a casing or other means arranged to direct the flow from the valveor nozzle over or along the said pipe, substantially as described.

4.- An apparatus for the separation of air into two parts, one rich inoxygen and the other poorin oxygen; and consisting of means `forliquefying the air and subjecting the said. liquid to fractionaldistillation by heat derived from compressed air about to be liquefied,substantially as described.

v5. An apparatus for the separation of lair into two parts, one rich invoxygen and the other poorin oxygen; and consisting of means forliquefying the air, means for subjecting the said liquid to fractionaldistillation by 'heat derived from vcompressed air about tobe liqueed,and means for utilizing the distilled nitrogen to cool compressed-airabout to be liqueed, substantially as set forth.

6. An apparatus for the separation of air into two parts one rich inoxygen and the other poor in oxygen; and consisting of means forliquefying the air, means for subjecting the said liquid to fractionaldistillation by heat derived from compressed air about to be liquefied,and means for utilizing the distilledl oxygen to cool air about to` beliquefied', substantially as set forth.

7. An apparatus for liquefying gas cornprising a compressor C, arefrigerator K for cooling the compressed gas, a counter-currentapparatus Gl having a high-pressure channel and a low-pressure channelin which the gas travels in opposite directions separated byheat-conducting material, the high-pressure channel being connected atits inlet to the discharge-pipe of the compressor through thevrefrigerator K, the low-pressure channel being connected 'at its outletto the suction of compressor C, a collecting-chamberV, a valve Rconnected with the discharge end of the high-pressure channel of thecounter-current apparatus and adapted to permit of the discharge of thecompressed gas from the highpressure channel directly into thecollectingchamber V', and a c'onnection'k between thev .collectingvessel V and the inlet end of the low-pressure channel, whereby theexpanded gas is conducted backwardly over and in direct contact with thehigh-pressure channel and caused to absorb heat to its fullest capacityfrom the compressed gas about to be expanded, substantially as setforth.

'8. An apparatus for liquefying gas com- IIC prising a primarycompressor P, a compressor adapt-ed to receive, compress and circulatethe gas supplied-by compressor P, a refrigerator K for cooling thecompressed gas, a counter-current lapparatus G' having a highpressurechannel and a low-pressure channel Y in which the gas travels inopposite directions separated by heat-conducting material, thehigh-pressure channel being connected at its inlet to the discharge-pipeof the compressor through the refrigerator K, the low-pressure channelbeing connected at its outlet to the suction of compressor C, acollecting-chamber V', a valve R' connected with the discharge end ofthe high-pressure channel of the counter-current apparatus and adaptedt0 permit of the discharge of the compressed gas from the high-pressurechannel directly into the collecting-chamber V' and a connection 7abetween the collecting-chamber V' and the inlet end of the low-pressurechannel, whereby the expanded gas is conducted backwardly overand indirect contact with the high-pressure channel and caused to absorb heatto its fullest capacity from the compressed gas about to be expanded,substantially as set forth.

9. An apparatus forliquefyinggas embodying a primary compressor P forsupplying gas at a comparatively low pressure a compressor C forcompressing the gas to a high pressure; a refrigerator containing acoiled pipe connected at its upper end to the discharge-opening of thecompressor C; a counter-current apparatus G' consisting of twoconcentric metallic pipes, spirally wound and forming an inner channelfor the passage of gas at high pressure, and an outer annular channelfor the gas at lower pressure; a closed collecting vessel V' beneath thecounter-current apparatus; a Valved nozzle N connected to the lower endof the inner channel of the countercurrent apparatus and projecting intothe vessel V'; a passage connecting the top of the vessel V' with thelower end of the annular channel of the counter-current apparatus;connections between the upper end of the high-pressure channel of theapparatus G' and the lower end ot' the refrigerator-coil and between theupper end of the annular channel of the apparatus G' and the compressorC; and a valved discharge at the bottom of the vessel V', substantiallyas described.

l0. An apparatus for liquefying and separating gases consisting of aprimary coinpressor P; a compressor Carranged to receive and compresscirculating gas, and fresh gas, or both; a refrigerator K connected atits top with the discharge-opening of the compressor C; acounter-current apparatus with high and low pressure channels separatedby conducting material; a closed collecting vessel V'; a valved nozzle Nconnected at its top with the lower end of the high-pressure channel ofthe counter-current apparatus; a connecting-channel 7c between the topof the collecting vessel V' and the lower end ofthe lowpressure channelof the counter-current apparatus; pipe connections between the upper endof the high-pressure channel of the apparatus G' and the lower end ofthe refrigerator, and between the upper end of the lowpressure channeland the compressor C; an evaporatingvessel V2; avalved pipe connection hfrom the bottom of the vessel V' to the bottom of the vessel V2; a coilS within the vessel V2; a valved pipe connection g from above the valveR to the lower end of the coil S, the upper end of the coil S beingconnected to the lower end of the inner channel of the counter-currentapparatus G2; a valved pipe connection from the upper end of the innerchannel of the counter-current apparatus G2 to the compressor C and adischarge-pipe from the upper end of the outer channel, substantially asspecified.

ll. In an apparatus forliquefying and separating gases, the combinationof the compressors P and C, refrigerator K, counter-current apparatus G'and G2, collecting Vessel V', evaporating vessel V2 with coil S,jet-nozzle N and connections substantially as shown and described, of acounter-current apparatus G3 having the upper end of its inner channelconnected with the supply of compressed gases through the pipef andvalve fm and the lower end of said channel connected to the valved pipeg and thence to the expansionnozzle N also, a pipe connection from thelower end ot the outer channel of apparatus G3 to the upper end of theVessel V2, and a discharge-pipe from the upper end of the outer channelof G3, substantially as described.

l2. An apparatus for the separation of air into two parts, one rich inoxygen and the other poor in oxygen; and consisting of means forliquefying the air and subjecting the said liquid to fractionaldistillation by heat derived from previously-cooled air undergoingcondensation at a higher pressure.

13. An apparatus for the separation of air into two parts, one rich inoxygen and the other poor in oxygen; and consisting of means forliquefyng the air, means for subjecting the said liquid to fractionaldistillation by heat derived from previously-cooled air undergoingcondensation at a higher pressure, and means for wholly or partlymaintaining the supply of said liquid by liquid air thus produced.

14. An apparatus for the separation of air into two parts, one rich inoxygen and the other poor in oxygen; and consisting of means forliquefying the air, means for subjecting the said liquid to fractionaldistillation by heat derived from previously-cooled air undergoingcondensation at a higher pressure, and means for utilizing the productsof distillation to cool air about to be liquefied.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

CARL LINDE.

Witnesses:

FLORENCE T. MoDoNALD, ANDREAS SoRG.

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